James J. Jeffries (1899-1905) retired as champion with a record of 19-0-2, and is still ranked the 7th greatest heavyweight of all time by the International Boxing Research Organization, more than a century after his last fight. He would suffer his only defeat when attempting a comeback following six years out of the ring to face then-champion Jack Johnson in 1910.

Jack Johnson (1908-15) was the first African-American Heavyweight Champion and a controversial figure throughout his career. The unstoppable Johnson would later be called "the world's greatest defensive fighter" by the man whom he defeated to win the championship, Tommy Burns.

Above and below: American Tobacco, Hassan Cigarettes 1910

Jess Willard (1915-19)

Burstein Isaacs & Co., Empress Cigarettes (UK)

Jack Dempsey, "The Manassa Mauler" (1919-26), was considered in some circles an unpopular champion during his reign, accused of having dodged the WWI draft. It wasn't until he lost to Gene Tunney in a championship bout infamous for its "long count" on the felled Tunney that Dempsey became the beloved figure he was remembered as in later years.

Above: Dempsey appears with Bob Hope (left) and Bing Crosby at a PGA Servicemen's Rehabilitation Fund golf tournament during World War II.

Gene Tunney, "The Fighting Marine" (1926-28), was undefeated as a heavyweight, though he lost one fight as a light heavyweight (to Harry Greb, who, like Tunney, is considered one of the best ever). His overall record was 81-1-3.

Above: The World In Pictures: World Class Boxers (Germany), 1928

Below: Sport Kings Gum, 1933

Max Schmeling (1930-32), the only man to defeat Joe Louis in Joe's prime. He would pay the price in the rematch, when Louis won by TKO at 2:04 into the first round, after knocking Schmeling to the canvas three times and cracking several of the German boxer's vertebrae. Both matches carried heavy sociopolitical overtones, as, with World War II looming on the horizon, Schmeling represented Adolph Hitler's "master race." Years later Louis and Schmeling would become great friends.

Above: Churchman's Cigarettes Boxing Personalities, 1938

Below: Greiling-Sportbilder (Germany), early 1930s

Following: Ardath Tobacco (UK), 1930s

Jack Sharkey (1932-33)

Greiling-Sportbilder (Germany), early 1930s

Primo Carnera (1933-34)

Churchman's Cigarettes Boxing Personalities, 1938

Max Baer (1934-35)

Churchman's Cigarettes Boxing Personalities, 1938

James J. Braddock, "The Cinderella Man" (1935-37)

Churchman's Cigarettes Boxing Personalities, 1938

Joe Louis, "The Brown Bomber" (1937-49), amassed a 69-3 record, though two of those defeats came after his initial retirement, during an ill-fated attempt at a comeback. He was the Heavyweight Champion for 11 years, 10 months, a record. In 2005, Louis was ranked the #1 heavyweight of all time by the International Boxing Research Organization.

Above: Churchman's Cigarettes Boxing Personalities, 1938

Full ticket from the second Louis-Schmeling fight, 6-22-38

Below: Leaf Gum, 1948

Following:

Topps Ringside, 1951

Time magazine, 9-29-41

Sport magazine, June 1948

Cigarette advertising card, 1950

Ezzard Charles (1949-51)

Topps Ringside, 1951

Jersey Joe Walcott (1951-52)

Topps Ringside, 1951

Rocky Marciano, "The Brockton Blockbuster" (1952-56), is the only Heavyweight Champion ever to retire undefeated (49-0).

Above: Topps Ringside, 1951

Below:

Full ticket from the second Marciano-Walcott championship fight, 5-15-53

Following:

Press photo from the second Marciano-Walcott fight, 5-15-53

Above: Rocky has just sent Jersey Joe to the canvas for a KO at 2:25 into the first round, successfully defending his title.

Above: Rocky's second duel with Roland La Starza, as depicted on the cover of the fall 1953 issue of Fight magazine. La Starza probably came closer than anyone to defeating Marciano when they first met in 1950, with Rocky winning by the only split decision of his professional career. Their 1953 rematch was a more decisive affair, Rocky defeating La Starza by TKO after knocking him through the ropes in the 11th round.

Below: Sports Illustrated, 9-19-55

Floyd Patterson (1956-59, 1960-62), the first Heavyweight to win back the title after having lost it. Between 1959 and 1961, he yielded the title to Sweden's Ingemar Johansson, regained it, then retained it in what was perhaps the most storied trio of Heavyweight championship fights in history until the legendary Ali-Frazier triumvirate of the 1970s.

Above: Collector card, Serie N (Belgium), 1962

Below: Signed photo

Ingemar Johansson, "The Hammer of Thor" (1959-60)

Above: Top Flight Stars, 1959

Below: Sports Illustrated, 7-6-59

Former champ Ingemar Johansson and champ Floyd Patterson at a Boxing Writers Association dinner in 1961.

AP wire photo, 1961

The fearsome and mysterious Charles L. "Sonny" Liston (1962-64).

Above: Panini Campioni Dello Sport (Italy), 1969

Below: Sports Illustrated, 9-17-62

Cassius Clay/Muhammad Ali (1964-67, 1974-78, 1978-79), who it’s probably safe to say was a legend in his own time, is the only Heavyweight Champion to have held that title three times. Never a stranger to controversy, he was stripped of his crown in 1967 after refusing to report for induction into the U.S. Army, and was not allowed to box again until late 1970. After being reinstated in 1971 (the U.S. Supreme Court unanimously overturned his conviction), he would regain the Heavyweight title in 1974 and again in 1978. He retired in 1979 with a 56-3 record, later attempting a comeback that resulted in a 1980 WBC title bout loss to reigning champion Larry Holmes. He would go down to defeat one more time, vs. Trevor Berbick in 1981, before calling it quits for good.

Above: Sports Illustrated, 5-24-65

Barratt & Co. Ltd. Famous Sportsmen (UK), 1971

Below: Brooke Bond & Co. Olympic Greats (UK), 1979

Following: Sports Illustrated, 5-5-69

Joe Frazier, "Smokin' Joe" (1970-73), he of the deadly left hook, decked Ali in the 15th round of their championship match of March 8, 1971 (billed as the Fight of the Century), helping secure a unanimous decision in favor of the then-undefeated champion. He would fight Ali two more times, in 1974 and 1975, losing both bitterly contested encounters.

Above: Keisa Campeones Del Deporte Mundial (Spain), 1974

Below: Sports Illustrated, 3-15-71

Following: Life magazine, 3-19-71

George Foreman (1973-74). The most devastating heavyweight puncher since Sonny Liston, Foreman knocked down the formidable Joe Frazier six times during their 1973 championship bout to win the title by TKO. Foreman is pictured above, just prior to the Frazier fight, with former Light Heavyweight Champion Archie Moore, "The Old Mongoose," who was an advisor in Foreman's training camp. In the early 1960s a young Cassius Clay had trained with Moore, from whom he learned a defensive maneuver Moore called the "turtle shell." Ironically, in his 1974 championship fight with Foreman, Clay (by then Muhammad Ali) would employ Moore's strategy to re-take the title. It became popularly known as the "rope-a-dope."

At the age of 45 Foreman reclaimed the crown he had lost 20 years earlier, becoming the oldest Heavyweight champion in boxing history (1994-95).

Above: AP wire photo, 1973

Below: Panini Sport Vedettes (Italy) 1973-74

Following: Sports Illustrated, 12-15-75

Leon Spinks (1978) beat Muhammad Ali in a split decision to win the Heavyweight title on February 15, 1978, only to lose it to him in the rematch seven months later.

Above: Sports Illustrated, 9-25-78

Below: Panini (Italy), 1976

Ken Norton (1978) was briefly the WBC Heavyweight Champion, until losing a very close split decision to Larry Holmes in his first and only title defense. Five years earlier he had broken Ali's jaw while handing the then-former champ his second defeat.

Sports Illustrated, 6-12-78

Larry Holmes (1978-85), who had held the WBC title since June of 1978, defeated Ali (who had relinquished the WBA title in April of 1979) on October 2, 1980, en route to 48 consecutive professional wins—one shy of Rocky Marciano's record of 49. He would finish his career at 69-6 in 2002.

Georges Carpentier (Light Heavyweight Champion, 1920-22) of France fought Jack Dempsey for the Heavyweight championship on July 2, 1921 in one of many bouts that would be dubbed "The Fight of the Century." It was the first title fight to be broadcast on radio and the first million dollar gate in boxing history. Dempsey, who outweighed Carpentier by 20 pounds, knocked out the challenger in the 4th round.

Teofani & Co. Magnums (England), 1925

Harry Greb (Middleweight Champion, 1923-26), the only man ever to defeat Gene Tunney (when both were light heavyweights). In 2005 the International Boxing Research Organization voted Greb the best Middleweight fighter of all time.

Billy Conn (Light Heavyweight Champ, 1939-40) relinquished his title to fight Joe Louis for the Heavyweight crown in 1941. He almost succeeded when, leading on points after twelve rounds, he decided to go for the knockout in the 13th. Louis KO'd him instead.

Rocky Graziano (Middleweight Champ, 1947-48) won 67 professional bouts, 52 by knockout. His life story was the subject of the 1956 MGM motion picture Somebody Up There Likes Me, which starred Paul Newman.

The Ring magazine, September 1949

Joey Maxim (Light Heavyweight Champion, 1950-52) didn't get a shot at the Light Heavyweight title until his 88th professional fight. His second defense of that title (on 6-25-52) was notable in that it was the only time challenger Sugar Ray Robinson was ever stopped in a fight—though Maxim got an assist from a record heatwave (it was 103 degrees in Yankee Stadium that day), causing Sugar Ray to fall victim to hyperthermia.

Topps Ringside, 1951

French air mail stamp commemorating the Middleweight Championship bout of 9-21-48 between defending champ Tony Zale (1940-47, 1948) and French challenger Marcel Cerdan. Cerdan defeated Zale to take the title.

Jake LaMotta (Middleweight Champ, 1949-51)Topps Ringside, 1951

Marcel Cerdan (Middleweight Champ, 1948-49)Leaf Gum, 1948

Ticket stub from the Cerdan-LaMotta championship fight, 6-15-49, in which Jake "The Bronx Bull" LaMotta won the Middleweight belt.

Carmen Basilio gave up his twice-won Welterweight Championship belt (1955-56, 1956-57) when he defeated Sugar Ray Robinson for the Middleweight Championship (1957-58) on September 23, 1957. Robinson would take back the title from Basilio six months later in a controversial split decision.

Sport magazine, February 1958

Gene Fullmer (Middleweight Champ, 1957, 1959-62) beat Sugar Ray to take the Middleweight crown for the first time in January 1957, only to be KO'd by Robinson's "perfect left hook" four months later. Fullmer defeated Basilio in 1959 to win the title a second time, retaining it until being beaten by Dick Tiger in 1962.